Method and apparatus for producing bulky continuous filament yarn



Jan. 23, 1962 A. L. BREEN 3,017,737

METHOD AND APPARATUS FOR PRODUCING BULKY CONTINUOUS FILAMENT YARN Filed June 25, 1958 IN VENTOR ATTORNEY 3,017,737 METHOD AND APPARATUS lFtJR PRGDUCING BULKY GUNTINUQUS FHLAMENT YARN Alvin L. Breen, West (Ihester, Pa, assignor to E. I. du

Pont de Nemours and Company, Wilmington, Del, a

corporation of Delaware Filed June 25, 1958, Ser. No. 744,592 6 Claims. (Cl. 57-34) This invention relates to process and apparatus for treating a bundle of continuous filaments, such as a yarn or thread, to produce a multifilament yarn of greatly increased bulk, and to the novel bulky yarn produced. More particularly, the invention claimed herein relates to a process and apparatus for preparing a bulky yarn composed of a plurality of individually convoluted filaments.

This application is a continuation-in-part of my copending application, Serial No. 375,372, filed August 20, 1953, now Patent No. 2,852,966, which is a continuationin-part of Serial No. 261,635, filed December 14, 1951, now Patent No. 2,783,609.

With the outstanding exception of silk, all natural animal, vegetable and mineral fibers exist in only relatively short lengths. The production of yarn from such staple fiber is a time-consuming operation which usually requires a complex series of operations to align the fibers, combine them into an elongated bundle, and draw the bundle to smaller diameter while twisting to prevent excessive slipping of adjacent fibers past each other. Further spinning operations finally produce yarn or thread useful in textile operations.

' atet All, or nearly all, artificial fibers are produced most easily as continuous filaments. Formation of continuous filaments into yarn is much simpler than staple processing. Continuous filament yarns may be made very strong because of the absence of loose ends that are unable to transmit imposed stresses. However, because of their extreme uniformity and lack of discontinuities, conventional continuous filament yarns are much denser than their staple counterparts. The filaments lie close together in the yarn, and adjacent strands of continuous filament yarn in fabrics are closely spaced. This compactness limits the amount of insulating air space present. The lack of occluded air space greatly restricts the usefulness of such continuous filament fabrics. Lightness, covering effectiveness, and warmth-giving bulk are essential for many uses. Hence a large amount of the total continuous filament production of such fibers as viscose rayon, cellulose acetate, nylon and polyacrylonitrile has been cut into short lengths for spinning into staple yarn.

Previous efforts to produce continuous filament yarn having the desirable qualities of staple yarn have been unsuccessful. marily with modifying the internal structure of the filaments', as by physical or chemical distortion. Mechanical crimping or twisting of filaments has produced undulating or spiralled fibers, but the effect has been disappointing. Similar unsatisfactory results have been obtained by imparting motion to the spinning head and by chemical treatment of the spun filaments. All known methods have been unsatisfactory for one reason or another, such as insufiicient bulkiness, unsatisfactory distribution of stress-bearing portions of the filaments, undesirable modification of fiber properties, i-mpermanence of form, or complexity and expense of the operations.

It is an object of the present invention to provide a continuous filament yarn of the thick and thin type having a b-ulkiness at least in portions as great as that of staple yarn spun from comparable fibers and having the same average number of filaments per crosssection. Another object is to provide multifilament variable thick- These efforts have been concerned pri-' ness yarn resembling spun staple in its desirable lightness, covering elfectiveness and warmth-giving bulk but retaining the characteristic continuous filament freedom from loose ends, fuzziness and pilling. Another object is to provide bulky multifilament yarns of finer denier than can be spun practicably from staple. A further object is to provide a process and apparatus for preparing continuous filament yarn having a bulk equal or superior to that of comparable staple yarn Without abrading or cutting the constituent filaments and without deforming or otherwise modifying their structure. A still further object is to provide such a process which is suitable for rapid-1y andeconomically treating ordinary multifilament continuous yarn to greatly increase the bulk without the use of moving mechanical parts other than in the windup and possibly in the means for varying or fluctuating the yarn tension. Yet another object is to provide suitable apparatus for preparing yarns of varying bulk along their length. Other objects of the invention will become apparent from the following description and claims.

In this invention, a yarn together with apparatus for making the same fulfilling the above objectives has been produced, composed of a plurality of substantially continuous, individually convoluted filaments. The individual filaments have coils, loops or whorls at random intervals along their lengths. The most obvious characteristics of the novel continuous filament yarn are its bulkiness and the presence of a multitude of filament loops irregularly spaced along its surface. These readily visible filament loops contributed to bulkiness, but the less obvious convolution-s of the filaments within the yarn provide a lateral interfilament spacing which is important in producing the bulk and resulting garment warmth of fabrics made from this yarn.

The convolutions of the filaments may be held in place by the twist usually imparted to yarn. When this is done, the absence of internal structural change may be shown by untwisting the yarn and taking it apart, whereupon the individual filaments will return to substantially their original condition. When ordinary straight filaments are used to prepare the bulky yarn, substantially straight filaments are obtained by unbulking the yarn, except where a setting treatment is applied prior to yarn disassembly or where the filaments are of such a nature as to take a permanent set in the textured form. Of course, crimped, wavy or curly filaments could be processed according to this invention, and such filaments would resume their respective starting configurations when separated from the yarn. Some reduction of tensile strength below that of ordinary continuous filament yarn may be expected because, at any given point in the bulked yarn of this invention, some of the filaments may not be placed under tension when the yarn is pulled, but this may be minimized or offset by increased twist, production of the loop-within-a-loop configuration described below, or by a treatment, such as steaming, to impart a permanent set.

A similar yarn might be prepared from a bundle of continuous filaments by tedious hand manipulation. An individual filament would be separted and slack formed in the filament. The slack would be taken up by forming a minute coil or loop in the filament and holding it in place by twisting the filament bundle or by encircling this loop by a similar convolution formed in a nearby filament. Repetition of this operation at intervals along each and every filament could eventually give the desired yarn structure.

In accordance with this invention a process has been devised for producing the described yarn structure rapidly with surprising simplicity.

In one preferred process of this invention, a stream of air or other compressible fluid is jetted rapidly from a confined space to form a turbulent region. Yarn to be treated is fed continuously or under varying and fluctuating tension into the fluid stream so that the yarn is supported by it and the individual filaments are separated from each other and whipped about violently in the turbulent region. Merely removing these separated filaments from the turbulent region for reassembly into a yarn accomplishes the desired result of forming loops and other convolutions at random intervals along each filament and irregularly spaced on different filaments. The filaments are whipped about in the turbulent zone sufficiently to form convolutions that are retained during Withdrawal, windup and further processing.

The invention will be better understood by reference to the drawings. In these drawings, which illustrate preferred embodiments of the invention,

FIGURE 1 is a schematic perspective view of suitable equipment for manufacturing bulky continuous filament yarn in accordance with the invention,

FIGURE 2 is a side view showing the appearance of untreated yarn being fed to the air jet (enlarged about ten times),

FIGURE 3 is a side view of the yarn leaving the air jet and being pulled downward out of the turbulent zone (enlarged about ten times),

FIGURE 4 is a side view showing the appearance of treated yarn before twist is applied (enlarged about ten times),

FIGURE 5 is a side view showing the appearance of bulky yarn after twist has been applied (enlarged about ten times),

FIGURE 6 is a diagrammatic view of a rotatable stopcock used for furnishing an interrupted flow of compressible fluid to the nozzle.

FIGURE 7 is a side view of yarn [treated by a modification of the bulking process (enlarged about ten times), with a portion having substantially no loops because of the variation in tension imparted by the pulsating jet,

FIGURE 8 is a modified form of air nozzle for use in practicing the invention.

Referring to FIGURE 1, the continuous filament yarn to be treated may be supplied from any suitable source, such as a yarn package supported on a creel 21. Untwisted yarn will normally be used, but twisted yarn can be used satisfactorily by increasing the filament-separating action, as shown later in the examples. The yarn can also be supplied directly from the spinning process by which it is produced, without any intermediate wind-up. The yarn 22, from whatever source is selected, passes through guides 23 and 24, between feed rolls 2 5 and 26, and to air nozzle 27. This nozzle consists of a compressed air pipe 28 screwed or brazed into yarn tube 2?, shown partly in section. The pipe and tube are arranged at an angle so that a flow of air is produced through the tube sutficient to carry the yarn along. The tube 29 can be as little as 1 inch long and 0.05 inch inside diameter.

The appearance of the yarn entering the air jet 27 is shown in FIGURE 2. The filaments are relatively straight and closely packed, giving the yarn a rod-like appearance. As shown in FIGURE 3, the yarn leaving the air jet is blown apart by the air stream. High speed motion pictures have shown that the individual filaments are whipped around violently by the turbulent air. As the filaments are withdrawn from the region of turbulence, they are swirled into convolutions which may be held in place by adjacent filaments of. the reforming yarn bundle. After passage through the turbulent zone and re forming into a yarn, the appearance of the bundle of filaments may be as shown in FIGURE 4. These filaments in some cases are only loosely grouped and a strong pull would remove the bulkiness if it were not stabilized by additional treatment, preferably by twisting the filaments together.

The loose bundle of filaments is directed by guides 30 and 31 to take-up rolls 32 and 33, and then passes to a wind-up device such as the down-twister shown. As is usual with this device, the yarn is given a twist as it is wound by passing through a traveller guide 34 sliding.

around on ring 35 mounted on ring rail 36. The yarn iscollected on spindle 37, supported by spindle rail 38 and rotated by belt 39, to form a package of finished yarn 40. The appearance of twisted yarn produced in this way is shown in FIGURE 5. In the actual yarn loops may be less than 1 millimeter in size. The loops and other convolutions of individual filaments are firmly held in place by friction between filaments. Increasing the twist increases this friction bctween filaments and holds the convolutions more firmly in place.

FIGURE 6 shows a stop-cock the stern of which is provided with a pulley or other means for rotating the core. Any other known means for intermittently interrupting the flow of air or other fluid to the nozzle 27 may be used. The tension on the yarn may also be intermittently increased and decreased, impulsed, fluctuated, or otherwise periodically or randomly varied by feed rollers, snubbers, slubbers, cams and the like. Suitable devices are shown in U.S. 386,623; 2,038,722; 2,116,660; 2,472,283; 2,562,760 and many others. All the examples may be modified by using these expedients to prepare thick and thin looped novelty yarns.

Movement of part 42 within jet body 45 so as to change the annular clearance between these parts nearest orifice I is a convenient method of causing fluctuations in air flow. Likewise, changes in alignment of these parts may be used to cause fluctuations in bulking efficiency. Sim-- ilarly an interrupting mechanism may be used to partially block the orifice 41 at random or periodic intervals.

If desired, yarn of the type shown in FIGURE 7 may be formed that requires little or no twist to provide relatively high yield points. The reason for the increased stability of this product is the frequent occurrence of snarls formed by entangled loops, e.g., a frequent encircling of the nodes of loops by other loops, most clearly seen at points a, b, and c in FIGURE 7. An attempt to stretch this modified yarn will cause tightening of many of the encircling loops, thus preventing encircled portions from unlooping, and holding the filament bundle together.

Yarn having the snarled or entangled loop structure is produced by a compounding of the ordinary looping action. This may be brought about in any one or more of a number of ways such as increasing the length of time the yarn is within the turbulent zone, increasing the turbulence in the zone, or setting up variations in the extent of turbulence. Adjustment of conditions to vary the bulky yarn produced according to this invention from the form shown in FIGURE 5 to the more complex structure of FIGURE 7, or to any intermediate configuration, must be determined by experiment in a particular case.

In the process of this invention it is only necessary for the yarn to be passed through a zone of sufficient turbulence for a sufficient distance to separate the filaments and form them into the described convolutions. The yarn need not be passed through an air jet or nozzle of the types described, but can be passed through a turbulent stream, howcver formed. Likewise, air need not be used as the turbulent medium; other gases or liquids can be used. Piezoelectric or magnetostrictive transducers might be employed with similar effect, but the fluid jet method is so inexpensive and easy to install, operate and maintain that it is naturally preferred, as the best known mode of operation.

The process has been specifically illustrated as used in connection with a downtwisting operation. However, it Will be obvious to one skilled in the art that the process may be practiced in conjunction with other yarn processing operations. Thus, by similar simple modifications of existing equipment, the process can be practiced on an uptwister, a cotton spinning frame or in spooling operations. As mentioned earlier, twisted yarn may be procis essed as well as untwisted yarn. If the yarn already has all of the twist desired, the yarn from the bulking treatment would be collected with a simple rewinder instead of a downtwister.

A fairly abrupt removal of the yarn from the turbulent region is conducive to formation of a better product. This may be accomplished by guiding or pulling the yarn from the turbulent stream, as described, or the turbulent stream may be diverted from the yarn by suitable means such as a baflie plate having a hole to admit the yarn. A baffie plate may be provided with a hole through which the yarn is passed, the air stream being deflected aside by the plate. The rate of windup as compared with the rate at which yarn is supplied to the jet, will limit the amount of bulking action possible by restricting the amount of reduction in length which occurs as the loops form.

The air pressure required depends upon the type of nozzle, the type of yarn, the yarn speed and the effect desired. In general, it is easier to obtain yarn uniformity when high air pressures are used, but the cost of compressing air makes it desirable to operate near the minimum pressure which will give adequate uniformity. 7

Higher pressures are required -for higher yarn speeds, but economics favor higher speeds "because the air cost per pound of product drops off rapidly as the through-put is increased. Useof a wide range of air pressures is illustrated in the examples which follow. The simple nozzle shown in FIGURE 1 requires quite high air pressures. Quite low air pressures were used with modified nozzles but such nozzles are relatively i-nefficient, in the amount of air used per pound of product, in comparison with the difiusor type of nozzle shown in my parent application. Typical air requirements for nozzles of the latter type when processing yarn at speeds of 50 to 100 yards per minute is about 40 pounds per square inch and between 1 and 4 cubic feet per minute at standard temperature and pressure. Similar observations apply when using other gases or Vapors such as steam.

The process and products of the invention will now be illustrated by the following examples, which are not to be construed as limiting the scope of the invention:

EXAMPLE 1 Apparatus equivalent to that in FIGURE 1, and using the nozzle shown in FIGURE 1 was used to process 150 denier, 40 filament, 0 twist, dull Acele cellulose acetate yarn. The yarn was unwound for treatment from a spool by the tension created by the fluid jet, with a friction tension device interposed between the spool and the nozzle to limit the yarn speed to approximately 13 yards per minute (calculated from the windup speed and ratio of final denier to starting denier). The nozzle was supp-lied with nitrogen at 150 pounds per square inch gage pressure, giving a gas consumption of approximately 0.4 cubic foot per minute at 760 mm. and 70 F. The yarn was wound up at 10 yards per minute and twisted to 6 turns per inch with an up-twister. The finished bulky yarn had a denier of 195 and the average filament loop size was about 0.5 mm.

The yarn treatment was repeated with different gas pressures and diiIerent yarn speeds to show how the size of the filament loops was affected. The changed conditions and the resulting loop sizes are given in Table I. The loop sizes are compared qualitatively because they are difi'icult to classify numerically. Generally speaking, however, VS. (very small) means that most of the loops were less than 0.5 mm. in size, small means that the predominating loop size was about 0.40 to 0.75 mm., medium means that the predominating loop size was about 0.5 to 1.5 mm-., and large means that most of the loops were over 1.5 mm. in size.

Table I EFFECT OF VARYING OPEIStfAi'gING CONDITIONS ON L001 A B G D Gas pressure- 150 150 300 390 Lbs/sq. in. gage. Yarn feed 54 31 54 54 YdsJmin. Yarn wind-up 40 18 37 35 Yds./min. Loop size Large Medium Small V.S.

EXAMPLE 2 Apparatus of the type shown in FIGURE 1, but using a modified nozzle, was used to process 150 denier, filament, 0 twist, dull Acele yarn. The yarn was fed to the air jet at 21 yards per minute and rewound after treatment at 18 yards per minute at a spindle speed of 5800 r.p.m. to impart a Z twist of 9 turns per inch. The air pressure was 5 lbs/sq. in. and the air consumption 0.21 cu. ft./min. The finished yarn had a denier of 175, a tenacity of 0.71, and an elongation of 20.9%. Untreated 8 Z twist yarn had a denier of 150, a tenacity of 1.2, and an elongation of 26.

EXAMPLE 3 Apparatus of the type shown in FIGURE 1, but using a modified nozzle, was used to process 200 denier, 80 filament, 0.32 twist, bright yarn of Orlon acrylic fiber. The yarn was fed to the air jet at 27.5 yards per minute and rewound after treatment at 22.8 yards per minute at a spindle speed of 4700 r.p.m. to impart a Z twist of 6 turns per inch. The air pressure was 15 lbs/sq. in. and the air consumption was 0.26 cu. ft./min. The finished yarn had a denier of 258, a tenacity of 1.98 and an elongation of 17.6. Untreated 6 Z twist yarn had a denier of 200, a tenacity of 4.0 and an. elongation of 19.

EXAMPLE 4 Apparatus of the type shown in FIGURE 1, but using a modified nozzle, was used to simultaneously blend and process denier, 60 filament, 2 S twist, bright textile Cordura" viscose rayon yarn and 150 denier, 40 filament, 0 twist dull Acele cellulose acetate yarn. The two yarns were unwound from separate spools and fed together to the air jet at 21 yards per minute. The treated blend was rewound at 18 yards per minute and a spindle speed of 5820 rpm. to impart a 9 Z twist. The air pressure was 10 lbs/sq. in. and the air consumption was 0.25 cu. ft/min. The finished yarn blend had a denier of 342, a tenacity of 0.74, and an elongation of 12.7. A similar blend which had not received the bulking treatment had a denier of 300, a tenacity of 1.27 and an elongation of 16%.

In Examples 1 to 4 the treatment increased the denier by 30.0%, 16.7%, 29.0% and 14.0%, respectively. This is some indication of the extent to which filaments have been formed into convolutions, but does not indicate the surprising increase in bulk which these convolutions impart to the yarn by maintaining the filaments in spaced relationship. In general, this increase in bulk is at least 80% for packaged yarn, as shown by the following two examples:

EXAMPLE 5 Apparatus of the type shown in FIGURE 1, but using the nozzle shown in FIGURE 8, was used to process 75 denier, 30 filament, 0.3 2 twist, bright yarn of Orlon arcylic fiber. The yarn was fed to the air jet at 54.0 yards per minute, treated with air supplied at 80 lbs/sq. in., and rewound after treatment at 45.0 yards per minute with a 3 S twist. The yarn was wound on a quill adapted for accurate measurement of volume at a tension of 20 grams. The yarn bulk was 3.3 cc./ gm. as compared with 1.2 cc./gm. for the untreated yarn, or an increase in bulk of The bulk was markedly superior to that of otherwise comparable spun staple yarn.

7 EXAMPLE 6 Apparatus of the type shown in FIGURE 1, but using the nozzle shown in FIGURE 8, was used to process 150 denier, twist dull Acele cellulose acetate yarn. Two plies of this yarn were fed simultaneously to the air jet at 21.6 yards per minute, treated with air supplied at 10 lbs/sq. in., and the combined treated yarn was rewound at 18.0 yards per minute with an 8 Z twist under a tension of 68 grams. The yarn bulk was 2.0 cc./gm. as compared with 1.1 'cc./ gm. for the untreated yarn, or an increase in bulk of 82%, even through the yarn was wound under considerable tension.

Since the purpose in treating yarn in accordance with this invention is to improve properties of fabrics in which it is used, the most practical way of showing the increase in bulk achieved is by observation made on such fabrics.

EXAMPLE 7 Fabrics were prepared in a 2 x 2 twill weave from untreated continuous filament viscose rayon yarn, from bulky yarn produced by treating the yarn in accordance with this invention, and from staple yarn spun from cut filaments. A comparison of the results is given in Table II. The bulk was measured by ASTM method D-76-49 at 3 lbs/sq. in. with an Ames gage.

Table II COMPARISON OF FABRICS WOVEN FROM THREE VISCOSE RAYON YARNS Type of yarn Denier Fabric Thickness Weight Bulk of yarn count; in inches oz./sq. yd. tee/gm.

300 63 x 60 0.013 5.01 1. 9 340 64 x 68 0.021 5. 95 2. 6 313 68 x 62 0.0195 5. 2. 0

EXAMPLE 8 Table III COMPARISON OF FABRICS WOVEN FROM THREE DIFFERENT YARNS OF "ORLON ACRYLIC FIBER Type of yarn Denier Fabric Thickness Weight Bulk of yarn count in inches oz./sq. yd. ccJgin.

Untreated 100 81 X 72 0. 006 2.12 2.1 125 80 X 64 0.015 2. 36 4. 8 Spun staple 133 93 x 60 0.0125 3. 32 2.8

The results of Examples 7 and 8 show the marked superiority in bulk of fabrics woven from the yarn of this invention in comparison with fabrics woven from ordinary continuous filament yarn. In general the increase in bulk is at least 30% when measured under the severe conditions described. The results also show that the bulky yarn may be equal, or even markedly superior, to spun yarn in this respect.

Bulky yarn can be prepared by the process of this invention from any continuous textile fibers regardless of their origin. However, since the filament convolutions of each filament are held in place by adjacent filaments, the process is operative only with multifilaments. The minimum number of filaments which can be processed satisfactorily into bulky yarn varies with the fiber, de-

pending upon such factors as smoothness of surface,

denier per filament, and the bending modulus, but any of the continuous multifilament materials referred to as yarn in the textile trade can be prepared in this bulk form.

The process described has been applied successfully to the production of bulky yarn from a wide variety of commercial fibers, as indicated in T able IV. In this table the starting material is designated by numbers indicating the yarn denier, the number of filaments and the twist in turns per inch, respectively, the type of twist, if any, and the trade designation. The designation nylon refers to polyhexamethylene adipamide and polythene refers to polymerized ethylene fibers. Orlon. Acele, and Dacron are trademarks of E. I. du Pont de Nemours and Company for acrylic, cellulose acetate and polyester fibers, respectively. Vinyon N is a vinyl chlorideacrylonitrile copolymer produced by Union Carbide and Carbon Corp. Fortisan is a high tenacity rayon regenerated by saponification of cellulose acetate and produced by the Celancse Corporation of America. Fiberglas is spun glass produced by Owens Corning Fiberglas Corp. The nozzle shown in FIGURE 8 was used in the examples of Table IV, with the indicated air pressure given in lbs./ sq. in. gage. The air consumption is in en. ft./min. at 760 mm. and F. Yarn speed is in yards per minute.

Table IV BULKY YARN PREPARATION FROM VARIOUS MATERIALS Ex. Yarn Speed Air Air Final No. Starting material feed windprescondenier up sure sump.

9 7034%Z nylon, 50 35 52 O. 68 286 150-40-0 Acclc. 10. 7034%Z nylon, 50 41 52 0. 68 169 -30-0 vise. rayon. 11 7034%Z nylon, 82 66 52 0.66 161 75-30-0 vise. rayon. 12- 7034 /Z Dacron-.. 50 38 48 1. 20 13. 40-34-VzS Dacron" 31 26 52 0.88 50 14- 40-34-VzS Dacron" 25 19 49 1. 24 54 15- 4034%S Dacron, 24 18 50 1. 25 247 150-40-() Acele. 16- 40-13-VzZ nylon, 24 18 50 1. 25 240 150-40-0 Acclc. 17. 4013%Z nylon 150 112 50 0.71 212 150-40-0 Ace e. 4013-V2Z nylon 50 36 40 1. 06 46 300-80-0 Acele 48 41 50 1. 18 359 3110-50-0 vise. rayon. 48 41 50 1. 18 345 3001200.3Z Orlon 48 41 50 1. 18 354 280136%Z nylon 48 41 52 1. 19 340 289-136-V Z Dacron. 48 42 60 1. 25 301 -60-0 visc. rayon, 38 26 68 1. 28 319 150-40-0 Accle. 70-34-AZ nylon, 38 26 68 1. 38 203 100-60-0 visc. rayon. 100400.3Z Orlon," 38 26 68 1. 28 243 100-60-0 vise. rayon. 100 60-0 visc. rayon, 38 26 68 1.28 201 70-34%Z Dacron." 28- Raw China silk 21 19 76 1. 34 149 29. 130l60-3Z 24 18 50 1. 21 164 Vinyon" N. 30 90-120-3Z Fortisan 21 17 43 1. 11 106 108-60 casein. 21 18 50 0. 93 130 110-115 Fibergl 21 20 70 1. 30 112 66207Z polythene.-. 21 18 41 l. 07 76 Example 4 has illustrated application of the bulking treatment to yarn having an initial twist of 2 turns per inch, and Examples 29, 30 and 33 (Table IV) have illustrated application of the treatment to yarns having initial twists of 3, 3 and 7 turns per inch, respectively. The other examples have been concerned with treatment of yarns having from 0 to /2 turns per inch of twist immediately after bulking, and have relied upon the windup device to introduce the desired twist, a downtwister being disclosed for this purpose. Table V further illustrates application of the process to several types of yarns which have a twist of about 5 turns per inch as they enter the bulking nozzle. This is an adequate twist for most uses, so they do not need to be twisted after bulking. In half of these examples the starting yarn had the desired final twist, while in the remainder the desired twist was introduced with an uptwister before bulking as indicated in the next to last line.

The examples of Table V were performed with the nozzle shown in FIGURE 10 of my parent application 9 using the apparatus shown in FIGURES 12 and 13 of that application for all except the examples having package sizes of 1.0 and 1.5, respectively, where the similar apparatus shown in FIGURE 14 of that application was used. The percent overfeed appearing in the table was calculated as follows:

Overfeed (percent) (100) tions, which may not be desirable. Stress-bearing filaments can also be used to provide stability, e.g., un'oulked filaments can be plied with bulked yarn, or some of the filaments passing through the air jet can be kept under such tension that little or no bulking of these stress-bearing filaments occurs. That is, a group or bundle of filaments can be fed to the air jet at a lower rate, e.g., at substantially the speed of the wind-up device, than the rest of the filaments, thereby keeping such group of filaments under tension and preventing the formation of loops therein.

Bulky yarn may be stabilized after production by treating it with size, wax, heat or chemicals to set the convolutions or hold them in place. Various procedures known to the prior art may be adapted to this purpose, and filaments may be set so firmly in the bulked configuration that they will retain their convolutions even though the twist, initially used to hold it in place, is removed.

Table V BULKING TREATMENT APPLIED TO TWISTED YARN Material Dac- Dac- Dac- Nylon Nylon Nylon Nylon Nylon Nylon Or- Rayon Acetate ron ron ron lon Starting denier 70 140 210 40 70 70 200 210 560 200 300 300 Filaments 34 68 102 34 34 34 65 102 272 80 50 80 Twist (t.p.i. Z) i .5 .5 5 .5 .5 5 0 5 5.0 5.0 5 0 5 0 5 0 Feed speed (y.p.m 45 45 45 45 45 100 45 300 65 45 45 45 Windup speed (y.p.m. 34 34 34 34 34 83 3t 2 50 34 34 .34 Overload (percent) 33 33 33 33 33 33 20 33 33 33 33 Final denier (nominal) 90 180 270 50 90 84 260 250 700 26" 390 100 Instability (percent) 1 6 4 2 3 2. 3 2 2 2 2 5.3 2 2 2. 0 Air pressure (p.s.i.) 4O 40 35 40 70 40 23 23 23 Air consumption (c.f.m.) 1 2.2 2.5 2 6 2.5 2 5 2. 5 2 5 4 2.5 1 5 1 7 1 5 Needle Size (I.D., 0.001 in 16 16 28 16 16 20 16 20 20 20 20 Venturi throat (0.001 in.) 70 70 70 70 60 60 70 60 70 70 70 70 Spindle speed (r.p.m.) 7, 300 7, 300 7, 300 7, 300 7, 300 0 7, 300 0 0 0 0 0 Twist added (turns) 4. 5 4. 5 4 5 4. 5 4. 5 0 4. 5 0 0 0 0 0 Package size (lbs) .25 .25 25 .25 .25 1 0 25 1. 5 25 .25 .25 25 The percent instability is an indication of how well the yarn will process in knitting and weaving operations. It was determined by suspending a preload of 0.01 gram per denier by a length of the yarn measuring 1 meter as preloaded, increasing the load to a total of 0.5 gram per denier for 5 seconds, reducing the load to 0.05 gram per denier, and measuring the final length. The percent increase in length is the percent instability given in the table.

It is important that the bulked yarn be stabilized against such permanent deformation under the stresses it will encounter in processing and use. The yarn leaves the air jet under little or no tension, and some of the convolutions introduced are easily removed even from yarn having a high twist. One way to stabilize the yarn is to prestress it under a greater tension than it will subsequently encounter. This removes convolutions which are not sufficiently firmly locked in place but, of course, also reduces the bulkiness. The process as illustrated has included this prestressing as a part of the windup operation. Thus, in the examples of Table V, the bulked yarn is stressed during passage from the tension guide to the windup roll, or between the draw feed roll and the windup roll. When using a downtwister, as illustrated in FIGURE 1, the yarn is stressed during passage from takeup rolls 32, 33 to the downtwister.

Such prestressing sometimes reduces the effectiveness of the bulking treatment by an undesirable amount. The stability can be improved by increasing the twist, but low twist yarns are often required. When applying the bulking treatment to yarn which has been twisted, as with the uptwister adaptation described, a knotty or nubby yarn will be produced if the twist is too high, although this eifect may sometimes be desirable. The entangled loop structure discussed in connection with FIGURE 7 provides improved stability, and this may be obtained by using lower yarn speeds or higher air pressures or higher overfeeds. These all involve changes in operating condi- The proper use of sizing has been found to make 10W twist yarn completely stable against loss of bulk during further textile processing. For example, a 7034- /2 Z nylon yarn was bulked 33% and single end sized in a continuous operation, depositing 8% of polyacrylic acid size on the yarn in the form of a 10% aqueous solution with a size roll rotating at 4- revolutions per minute in a direction opposite to the yarn. This yarn was completely stable to stresses up to the breaking tension. When woven as filling yarn in a 7034 continuous filament nylon warp, no loss of bulk in fabric form and no difference in pill resistance was noted in comparison with the same starting yarn bulked and twisted to 86345 2. These two yarns were also knitted into socks, which were finished and dyed. The hand, bulk, covering power and run resistance of the /2 twist, sized-yarn socks appeared to be superior to that of the corresponding socks knitted of unsized 5 Z twist yarn. Single and sizing of bulked yarn should be accomplished before windup because loss of bulk occurs when removing the unsized bulky yarn from a package. An alternative method is to apply the size to the yarn package.

Heat-setting, especially steaming, efiectively improves stability. Appropriate temperatures and procedures for a given material will be similar to treatments used in the prior art for twist or fabric setting. As an illustration, a 70-34-5 2 nylon was bulked at 33% overfeed and heat set by three methods:

(a) Hot air at F. wet bulb, F. dry bulb, for 2 hours,

(b) Steam at 227 F. for 90 minutes,

(0) Steam at 274 F. for 1 hour.

The amount of instability, determined as previously described, was reduced about 30% by treatment (a) and about 60% by treatment (5). Treatment (0) gave a somewhat better product and the treatment time was shorter.

Regenerated cellulose filaments which will crimp spontaneously when treated with a swelling agent are disclosed in US. Patent No. 2,515,834 to W. D. Nicoll. Bulky yarn formed with these filaments in the uncrimped condition will have the bulkiness improved by crimping the filaments as described in the patent, as by immersion in a warm dilute aqueous solution of caustic. Crimping in this way is also simpler because the filaments will crimp satisfactorily with the bulk yarn under tension whereas the filaments ordinarily have to be relaxed (free of tension) when crimped.

Table IV has illustrated the preparation of blended yarns by feeding two different types of yarns simultaneously to the air jet. Any number of yarns may be combined in this way. A uniform blend of different types of filaments can be prepared during the bulking treatment with no more difiiculty than when bulking yarn from a single source. This is an important advantage because of the increasing recognition being given to blends as a way of obtaining combinations of desirable textile properties not obtainable with a single type of fiber. Yarn composed of a mixture of staple fibers has been easy to prepare by conventional textile methods, but has been difiicult to accomplish with continuous filaments. Since the bulky yarn of this invention will compete with spun staple for many uses, it is fortunate that uniform mixtures are so easily prepared.

A different purpose for mixing two different fibers arises when preparing very low denier bulky yarns. If the yarn denier is too low to bulk satisfactorily it can be bulked in combination with a second material which is then removed with a solvent which does not affect the first material. For example, a 30 denier, l filament, bulked nylon yarn was found quite difiicult to prepare from nylon alone with a given equipment. It was readily prepared by bulking a filament nylon yarn simultaneously with a 30 filament acetate yarn to obtain a 130 denier bulked yarn and then removing the acetate filaments from the mixture by dissolving them in acetone. A mixture of fusible and infusible fibers could be processed in a similar way, using heat instead of a solvent.

Even when bulking a single type of fiber it is sometimes desirable to feed yarn simultaneously from more than one source of supply. In this way larger yarns can be built up. Furthermore, since knots will not ordinarily pass through a bulking nozzle, bulked yarn prepared from a single source will be limited in length by the length of 'yarn on the supply package. By feeding from more than one package, arranged so that the packages are not exhausted at the same time, bulked yarn can be made of any desired length by starting a new package as soon as a yarn end is reached.

This application has been primarily concerned with the production of uniform bulky yarn composed of continuous filaments. However, a number of novelty effects may be obtained by changes in the air flow. By using higher pressures to obtain high jet velocities a yarn structure was prepared which had the appearance of a hybrid between bulky continuous filament yarn and a staple yarn. Sutficient force was applied to break some of the filaments so that both loops and free ends were in evidence. With still higher velocity jets, all of the filaments are broken to produce fiock particles which may have a wide range of lengths. When using extremely low jet velocities and overt'eeding a knotty or nubby bulky yarn is produced. The knots are randomly spaced at intervals of about inch to 3 or more inches, depending on the conditions, and consist of complete convolutions of the entire yarn bundle except for a few filaments wrapped about the intersections with sufiicient tenacity to impart stability. A thick and thin yarn, wherein the thick sections contain most of the convolutions, is produced by a pulsating air jet or similar means to vary or fluctuate the tension on the feed yarn. Most of the above novelty effects are accentuated when treating a mixture of different types of filaments.

The most practical designs of air nozzles known have been disclosed, but the process is so flexible that a wide variety of nozzles can be used more or less satisfactorily. J etting devices which depart more widely from those shown include multiple orifices or multiple venturis and combinations of air jets in succcession to accentuate the bulking action. The turbulence of the jet may be increased by cross jets. The filament separation may be accomplished or supplemented by other means, such as an electrostatic field to induce like charges on the filaments, causing them to separate and balloon outward.

The advantages of this invention are many. The bulky yarn has the desirable properties of spun staple yarn and avoids the necessity of cutting continuous filaments into staple and then reforming the staple into yarn. The bulky yarn is simply and economically prepared, by a process which requires little equipment, directly from the continuous filament bundle initially produced in syntheticfiber manufacture. The bulky yarn is superior to spun staple for many purposes because of its freedom from loose ends. However, it can be made to resemble spun staple in this respect, if desired, by cutting or singeing the protruding filament loops to provide loose ends. The unmodified hand of fabrics made from the bulky yarn usually is stiffer than that of corresponding staple materials, making them more suitable for use in draperies, suits, overcoats, etc.

The yarn is sufficiently uniform to be handled easily by textile machinery and to form highly uniform fabrics without the sacrifice of bulk or of fiber interlocking characteristic of some mechanically crimped yarn having too regular a structural pattern. The yarn has been used without difficulty on both automatic weaving and automatic knitting machines. The increased covering effectiveness of fabric made with the bulky yarn permits the production of more fabric from the same weight of yarn and, in addition, by greatly extending the utility of artificial fibers, enables them to replace expensive or scarce fibers in many uses.

Another advantage is the suitability of this process to combining filaments of extremely fine denier into light bulky yarns, having a highly uniform appearance, for which there is no spun staple counterpart. More than one kind of filament may be processed simultaneously to create yarns with a desirable blend of fiber characteristics. Intermittent impulsing of the multifilament being processed can be used to produce a novelty yarn having alternating smooth lengths and bulked regions produced according to the described process.

The simplicity of the new process permits its use at any point in yarn manufacturing or winding with no interruption of processing routine and little outlay for new equipment. Distinct advantages of the process are that it requires little supervision, demands very little maintenance because of its freedom from moving parts, and does not involve temperature or humidity control.

Since many different embodiments of the invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited by the specific illustrations except to the extent defined in the following claims.

I claim:

1. Apparatus for making novelty yarns, which comprises a zone for separating and whipping about the filaments of a bundle of filaments supplied thereto to form convolutions in said filaments, means for supplying said bundle of filaments in the form of yarn to said zone, means for withdrawing said filaments from said zone and for reforming them into yarn under a tension sufficiently low to prevent said convolutions from straightening out whereby to form a bulky yarn, and means for intermittently increasing the tension on the filaments passing through said zone to produce a yarn the bulkiness of which varies intermittently along its length.

2. Apparatus for making bulky continuous filament yarn which comprises a fluid nozzle adapted to create a turbulent zone, means for feeding yarn through the turbulent zone means for supplying fluid to the said nozzle under a pressure to provide sufficient turbulence to separate the yarn filaments and form them into convolutions, means for intermittently varying the tension on the said yarn passing through said zone, and means for withdrawing the separated filaments from the turbulent zone and reforming them into yarn.

3. The apparatus of claim 2 in which the means for varying the tension on the yarn comprises means for pulsating the pressure of the fluid passing through the nozzle.

4. The process of making bulky continuous filament yarn from a bundle of substantially straight continuous filaments which comprises passing the filament bundle through a jet of a compressible fluid having sufficient force to separate the filaments and form them into individual convolutions, intermittently varying the tension on the yarn bundle passing through the jet, removing the filaments from the jetted fluid, and combining the convoluted filaments into a yarn while avoiding tension sufficient to remove the convolutions.

5. The process of claim 4 in which the tension on the yarn is fluctuated by impulsing the pressure on the compressible fluid passing through the said jet.

6. Process for the production of novelty yarn, which comprises passing a bundle of filaments through a zone wherein the filaments are separated and whipped about sufliciently to form convolutions of the filaments in said zone, removing the filaments from said zone under a tension sufiiciently low to prevent said convolutions from straightening out, twisting said filaments together to form a yarn which is bulky and has a multitude of loops spaced along its surface, and intermittently increasing the tension on the bundle passing through said zone to produce a yarn the bulkiness of which varies intermittently along its length.

References Cited in the file of this patent UNITED STATES PATENTS 1,898,085 Dreyfus et a1. Feb. 21, 1933 2,278,888 Lewis Apr. 7, 1942 2,472,283 Byers June 7, 1949 2,852,906 Breen Sept. 23, 1958 

1. APPARATUS FOR MAKING NOVELTY YARNS, WHICH COMPRISES A ZONE FOR SEPARATING AND WHIPPING ABOUT THE FILAMENTS OF A BUNDLE OF FILAMENTS SUPPLIED THERETO TO FORM CONVOLUTIONS IN SAID FILAMENTS, MEANS FOR SUPPLYING SAID BUNDLE OF FILAMENTS IN THE FORM OF YARN TO SAID ZONE, MEANS FOR WITHDRAWING SAID FILAMENTS FROM SAID ZONE AND FOR REFORMING THEM INTO YARN UNDER A TENSION SUFFICIENTLY LOW TO PREVENT SAID CONVOLUTIONS FROM STRAIGHTENING OUT 